48 



FLUORESCENCE OF THE URANYL SALTS. 



preparation which differs from most of the uranyl salts is the uranyl 

 sodium phosphate, a sample of which was made by D. T. Wilber for 

 certain studies in fluorescence recently published. 1 This substance is 

 a very viscous liquid with the characteristic green fluorescence of the 

 uranyl compounds. 



One might expect, in accordance with the findings of Becquerel for 

 liquids in general, 2 that there would be no observable after-glow. It 



EFFECT OF TEMPERATURE 



ON 

 URANYL AMMONIUM NITRATE 



20" 



30 



-180 



20 



10 



jQ07 SEC. 



FIG. 39. 



is true that Becquerel expressed the belief that with a phosphoroscope 

 of sufficient speed, phosphorescence would probably be detected in 

 fluorescent liquids, but no one, so far as we know, save Dewar in an 

 unconfirmed statement concerning a supposed phosphorescence of 

 liquid air, has since that time (1859) recorded an instance of phos- 

 phorescence excepting in solids and gases. 



When a tube containing the phosphate was tested with the syn- 

 chrono-phosphoroscope no phosphorescence was found of duration 



1 Howes and Wilber, Physical Review (2), vol. 7, p. 394. Mar. 1916. 



2 See E. Becquerel, La Lumiere, vol. i, chapter on Phosphorescence. 



